Abstract
Purpose :
Corneal angiogenesis, induced by various ocular insults, compromises corneal transparency. Our previous studies have shown that activation of ocular surface mast cells directly promote the development of new blood vessels. Here we investigated whether mast cells contribute to the stability of inflammatory blood vessels and impede vessel regression.
Methods :
Neovascularization was induced by placing a single figure-8 intrastromal suture in the cornea using 11-0 nylon. On day 9, the suture was removed upon establishment of mature blood vessels. Corneas were harvested and stained with avidin+ (mast cells) and CD31+ (vascular endothelial cells) for immunohistochemistry (IHC) analysis. Real-time vessel regression was followed by capturing slit-lamp pictures. To investigate the direct effect of mast cells on vessel regression, suture was placed in mast cell deficient cKitw-sh and their wildtype (WT) C57BL/6 controls. To evaluate the effect of pharmacological blockade of mast cells on the reversion of mature blood vessels, corneas were treated one day prior to suture removal with mast cell inhibitor, cromolyn (2% in PBS). Slit lamp images were analyzed using ImageJ software. Corneas were harvested on day of suture removal and 2 days post-suture removal and expression of angiogenic factor, VEGF, was quantified to assess vessel regression at the molecular level.
Results :
IHC analysis demonstrated an abundance of mast cells surrounding the new corneal blood vessels on day 9 post-suture. By 48 hours following suture removal, a significant 51.3% (± 0.67%) regression of blood vessels were observed in cKitw-sh mice, compared to 11.5% (± 2.15%) regression in WT controls (p=0.002). Established vessels completely regressed in cKitw-sh mice by day 7 post-suture removal. Moreover, cromolyn treatment promoted faster regression of inflammatory blood vessels, as demonstrated by complete regression of pathological vessels by 24 hours post-suture removal, compared to PBS treatment resulting in no significant change in the inflammatory vessels. Furthermore, molecular analysis of vessel regression showed a 59% lower expression of VEGF in the cromolyn-treated corneas, relative to PBS-treated groups (p=0.03).
Conclusions :
Our data demonstrate that deficiency of ocular surface mast cell function results in faster regression of pathologic corneal blood vessels, suggesting mast cells promote the stability of inflammatory vessels.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.